Quality of service aware data dissemination in vehicular Ad Hoc networks

Des systèmes de transport intelligents (STI) seront éventuellement fournis dans un proche avenir pour la sécurité et le confort des personnes lors de leurs déplacements sur les routes. Les réseaux ad-hoc véhiculaires (VANETs) représentent l'élément clé des STI. Les VANETs sont formés par des véhicules qui communiquent entre eux et avec l'infrastructure. En effet, les véhicules pourront échanger des messages qui comprennent, par exemple, des informations sur la circulation routière, les situations d'urgence et les divertissements. En particulier, les messages d'urgence sont diffusés par des véhicules en cas d'urgence (p.ex. un accident de voiture); afin de permettre aux conducteurs de réagir à temps (p.ex., ralentir), les messages d'urgence doivent être diffusés de manière fiable dans un délai très court. Dans les VANETs, il existe plusieurs facteurs, tels que le canal à pertes, les terminaux cachés, les interférences et la bande passante limitée, qui compliquent énormément la satisfaction des exigences de fiabilité et de délai des messages d'urgence. Dans cette thèse, en guise de première contribution, nous proposons un schéma de diffusion efficace à plusieurs sauts, appelé Dynamic Partitioning Scheme (DPS), pour diffuser les messages d'urgence. DPS calcule les tailles de partitions dynamiques et le calendrier de transmission pour chaque partition; à l'intérieur de la zone arrière de l'expéditeur, les partitions sont calculées de sorte qu'en moyenne chaque partition contient au moins un seul véhicule; l'objectif est de s'assurer que seul un véhicule dans la partition la plus éloignée (de l'expéditeur) est utilisé pour diffuser le message, jusqu'au saut suivant; ceci donne lieu à un délai d'un saut plus court. DPS assure une diffusion rapide des messages d'urgence. En outre, un nouveau mécanisme d'établissement de liaison, qui utilise des tonalités occupées, est proposé pour résoudre le problème du problème de terminal caché. Dans les VANETs, la Multidiffusion, c'est-à-dire la transmission d'un message d'une source à un nombre limité de véhicules connus en tant que destinations, est très importante. Par rapport à la diffusion unique, avec Multidiffusion, la source peut simultanément prendre en charge plusieurs destinations, via une arborescence de multidiffusion, ce qui permet d'économiser de la bande passante et de réduire la congestion du réseau. Cependant, puisque les VANETs ont une topologie dynamique, le maintien de la connectivité de l'arbre de multidiffusion est un problème majeur. Comme deuxième contribution, nous proposons deux approches pour modéliser l'utilisation totale de bande passante d'une arborescence de multidiffusion: (i) la première approche considère le nombre de segments de route impliqués dans l'arbre de multidiffusion et (ii) la seconde approche considère le nombre d'intersections relais dans l'arbre de multidiffusion. Une heuristique est proposée pour chaque approche. Pour assurer la qualité de service de l'arbre de multidiffusion, des procédures efficaces sont proposées pour le suivi des destinations et la surveillance de la qualité de service des segments de route. Comme troisième contribution, nous étudions le problème de la congestion causée par le routage du trafic de données dans les VANETs. Nous proposons (1) une approche de routage basée sur l’infonuagique qui, contrairement aux approches existantes, prend en compte les chemins de routage existants qui relaient déjà les données dans les VANETs. Les nouvelles demandes de routage sont traitées de sorte qu'aucun segment de route ne soit surchargé par plusieurs chemins de routage croisés. Au lieu d'acheminer les données en utilisant des chemins de routage sur un nombre limité de segments de route, notre approche équilibre la charge des données en utilisant des chemins de routage sur l'ensemble des tronçons routiers urbains, dans le but d'empêcher, dans la mesure du possible, les congestions locales dans les VANETs; et (2) une approche basée sur le réseau défini par logiciel (SDN) pour surveiller la connectivité VANET en temps réel et les délais de transmission sur chaque segment de route. Les données de surveillance sont utilisées en entrée de l'approche de routage.Intelligent Transportation Systems (ITS) will be eventually provided in the near future for both safety and comfort of people during their travel on the roads. Vehicular ad-hoc Networks (VANETs), represent the key component of ITS. VANETs consist of vehicles that communicate with each other and with the infrastructure. Indeed, vehicles will be able to exchange messages that include, for example, information about road traffic, emergency situations, and entertainment. Particularly, emergency messages are broadcasted by vehicles in case of an emergency (e.g., car accident); in order to allow drivers to react in time (e.g., slow down), emergency messages must be reliably disseminated with very short delay. In VANETs, there are several factors, such as lossy channel, hidden terminals, interferences and scarce bandwidth, which make satisfying reliability and delay requirements of emergency messages very challenging. In this thesis, as the first contribution, we propose a reliable time-efficient and multi-hop broadcasting scheme, called Dynamic Partitioning Scheme (DPS), to disseminate emergency messages. DPS computes dynamic partition sizes and the transmission schedule for each partition; inside the back area of the sender, the partitions are computed such that in average each partition contains at least a single vehicle; the objective is to ensure that only a vehicle in the farthest partition (from the sender) is used to disseminate the message, to next hop, resulting in shorter one hop delay. DPS ensures fast dissemination of emergency messages. Moreover, a new handshaking mechanism, that uses busy tones, is proposed to solve the problem of hidden terminal problem. In VANETs, Multicasting, i.e. delivering a message from a source to a limited known number of vehicles as destinations, is very important. Compared to Unicasting, with Multicasting, the source can simultaneously support multiple destinations, via a multicast tree, saving bandwidth and reducing overall communication congestion. However, since VANETs have a dynamic topology, maintaining the connectivity of the multicast tree is a major issue. As the second contribution, we propose two approaches to model total bandwidth usage of a multicast tree: (i) the first approach considers the number of road segments involved in the multicast tree and (ii) the second approach considers the number of relaying intersections involved in the multicast tree. A heuristic is proposed for each approach. To ensure QoS of the multicasting tree, efficient procedures are proposed for tracking destinations and monitoring QoS of road segments. As the third contribution, we study the problem of network congestion in routing data traffic in VANETs. We propose (1) a Cloud-based routing approach that, in opposition to existing approaches, takes into account existing routing paths which are already relaying data in VANETs. New routing requests are processed such that no road segment gets overloaded by multiple crossing routing paths. Instead of routing over a limited set of road segments, our approach balances the load of communication paths over the whole urban road segments, with the objective to prevent, whenever possible, local congestions in VANETs; and (2) a Software Defined Networking (SDN) based approach to monitor real-time VANETs connectivity and transmission delays on each road segment. The monitoring data is used as input to the routing approach

The management of auricular defect using retroauricular flap

Management of auricular defect is still a challenge for reconstructive plastic surgeons. The complexity of anatomy and shape will make the reconstruction complicated. It is also inevitable that choosing the right donor to close the defect that resembles the original contour is one of the success indicators of any ear reconstruction. There are wide selections of techniques for the management of auricular defect. Retroauricular flap is one of the best choices in auricular reconstruction due to its vascular richness, low of failure rate, similarity of tissue contour and the ease of closing the donor-site defect primarily. This article reported three cases of auricular defect with various causes: crushed injury, human bite, and tumor excision. Two stages of surgeries were performed on all three patients. After sufficient debridement, the ear defect is planted beneath retroauriculomastoid dermis. The second stage, three weeks from the first surgery, the donor flap is separated from it host. One week follow up after the second stage surgery, all of the post-operative wounds showed no signs of infection, minimal scar formation and has satisfied aesthetic outcomes. The retroauricular flap has the advantages of simple dissection, low failure rate and has a good shape, texture, color for a very good aesthetic results. This flap may be considered as a good solution in the management of auricular defect and a flap bank for ear reconstruction

Resection of localized cheek infantile hemangioma in the proliferative phase: a case report

Infantile hemangioma (IH) is the most common vascular tumor which is characterized by proliferative phase, involuting phase, and involuted phase. As the regression will ultimately occur at the end of the phase, the choice of treatment become controversial. Although surgical management often advocated for complicated and conservative therapy failure cases, early resection may give some benefits both to the patients and parents. This case report described a 9-month-old female with cheek IH who underwent tumor resection followed by cheek flap as the procedure to close the defect. After two days post-operation, the patient was discharged from hospital without any complication observed. The surgical scar was favorable in the first month after surgery. Early resection can be established as one of the treatment choices for fast-growing hemangioma in the proliferative phase to avoid undesirable aesthetic sequelae in the future

Influence of dietary prebiotic mixture (α-mune) on growth performance, haematology and innate immunity of Beluga sturgeon (Huso huso) juvenile

The present study investigated the effects of prebiotic (α-mune), a mixture of mannan oligosaccharide, β-1,3 and β-1,6 glucan, on the growth performance, haematology and innate immunity of beluga sturgeon (Huso huso) juvenile. Fish (46±3 g) were allocated into 12 tanks (15 fish per tank) and triplicate groups were fed a control diet or diets containing 1.5, 3.0 and 4.5 g kg-1 prebiotic for 46 days. Fish fed 1.5 g kg-1 prebiotic displayed significantly higher final weight, specific growth rate and feed conversion ratio. WBC, RBC, MCV, MCH, haemoglobin, haematocrit and lymphocyte levels were also significantly higher in the fish fed 1.5 g kg-1 prebiotic. Furthermore, the highest haematocrit content and lymphocyte level were found in the fish fed a diet containing 1.5 g kg-1 prebiotic. Alternative complement activity (ACH50), lysozyme activity and Ig concentration were significantly higher in the fed 1.5 g kg-1 prebiotic. These results indicate that α-mune can be considered as a beneficial dietary supplement for improving the growth performance, haematological and immunological parameters of beluga sturgeon juvenile